Facile method to align crystalline needles composed of organic semiconducting materials using a balance between centrifugal and capillary forces

摘要

Methods to align one-dimensional microstructures composed of organic materials have attracted much attentionbecause of their potential applications to devices such as field-effect transistors. Although dip coating is one of the methods(using self-assembly) used for the purpose, its disadvantage is that a larger amount of the material dissolves in the solutionthan what actually gets deposited on substrate. In this study, we developed a novel method that requires a small amountof precursor solution. By placing a polydimethylsiloxane block on a glass substrate and rotating the substrate using a spincoater, a small amount of the precursor solution was confined in a narrow region along the foot of the block.When we usedan organic semiconducting material, 9,10-dibromoanthracene, as a solute, aligned and roughly oriented crystalline needleswere precipitated. The thicknesses and lengths of the crystalline needles were controlled by the composition of the solventand the rotation speed.